If plastic is used, you want something that you can fill without difficulty, and that you can store upright and open easily without spilling and risking bacteria getting in the milk. We are more concerned about the container when the baby is exclusively fed pumped and stored milk. In this scenario, we prefer glass or special plastic containers that are made precisely to collect milk. Baggies shouldn’t be used. They don’t stand upright in the freezer, and when they are thawed it is more difficult to pour the milk in the bottle, thus increasing the risk of contamination. Also, sometimes those bags split in the freezer.

Not all plastics are the same. But if you are freezing milk in a plastic nursing bottle, it is probably a safe plastic. I wouldn’t worry, especially if your baby only gets breast milk from a bottle occasionally.

amy, thanks for letting us know. so back to square one i guess. my supply has been building up a bit lately in the fridge, so i'd like to start freezing before the pumped milk turns bad. with Avent bags gone, here are the freezer bag options, can someone pls help with the following?
- Lasinol bags with ziplock (how much are these?)
- Medela bags (how much are these?)
- Avent cups (can we use liners as freezer bags?) disposable cups would seem quite expensive...
- any other freezer bag options that more economical?
I like the idea of freezing them as cubes, do i need to double bag if i do that?

A less expensive alternative to the Avent bags are the Playtex bottle liners. Can't remember exactly how much, but definitely cheaper. I got mine from Bumps to Babes. Instead of twisties, I use plastic clips that you can get from either IKEA or Park n' Shop. I've been doing it this way for both LOs and so far no leaks.